In a study of 150 patients suffering from shock caused by injuries such as a gunshot wound, the drug didn't meet its main goals - including reducing the chance of multiple organ failure, Icos said. It also didn't meet secondary goals, including reducing the death-rate from shock at 28 days, the company said.

Icos is still testing the compound for different uses - including heart attack and stroke - which analysts said hold more promise. Still, the poor study results increase the pressure on Icos, analysts said.

"This puts increased importance on both the heart and the stroke studies," said Leslie Wright Marino, a BancBoston Robertson Stephens analyst. "The Icos strategy . . . of taking numerous indications and developing them in parallel is something that not many biotechs have the financial and managerial resources to be able to do."

Icos, which is also developing an impotence drug it hopes can challenge Pfizer's blockbuster Viagra, has attracted attention in part because of its prestigious board.

Still, the company has not yet won approval to market any of its product candidates, many of which are still in earlier stages of testing.

In addition to Gates - who held 11.7 percent of Icos, or 5 million shares, according to the most recent regulatory filings - other directors at Icos include Walter Wriston, former CEO of Citicorp; Frank Cary, former CEO of International Business Machines; and James Ferguson, former CEO of General Foods.

Shock is a notoriously difficult condition to treat, because by the time a patient enters shock from blood loss after a car accident or a gunshot wound, the body is malfunctioning at a number of levels, analysts said. That's one reason many analysts didn't have high expectations for this use of LeukArrest, Marino said.